I found the preamble at the beginning of the announcement charmingly dated:
> The Minor Planet Electronic Circulars contain information on unusual minor planets, routine data on comets and natural satellites, and occasional editorial announcements. They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
>
> Prepared using the Tamkin Foundation Computer Network
> The OpenVMS cluster consists of nine single-CPU workstations and one four-CPU server. All the machines are running the extremely robust and secure OpenVMS operating system. The twelve Alpha-based machines are arranged as an OpenVMS Cluster, allowing all machines to share disk storage, execution and batch queues and other resources, as well as simplifying system management.
Maybe not as old. I deployed a few racks of HP Alpha DS25s in 2007-2008 before they were replaced with Itanium based Blades (running OpenVMS 8.4). I do not miss working with OpenVMS one bit. It was rock stable (basically an on/off appliance) but the user experience left me wanting (coming from Linux).
I can see how they may be still stuck on Alphas because unless they can somehow simply recompile for x86-64 OpenVMS, it’s a complete rewrite from scratch.
bastardoperator · 9h ago
Could they not get more juice out of a single, modern server? I get porting over to a new system and migrating is a huge time suck and a good enough reason not to do it if everything is working, just seems excessive for 14 cores.
Macha · 9h ago
> Could they not get more juice out of a single, modern server
They could probably get more performance out of one core on a modern phone, never mind a single modern server. But you see some really old systems in a lot of equipment, not because the porting costs are expensive, but the certification of proving the new system works the same is more than the operational cost of the legacy equipment.
api · 8h ago
I’ve heard of consultants who will virtualize systems like this in place using qemu emulation of CPUs like Alpha and Sparc and run it on a single server or in the cloud.
dragonwriter · 5h ago
Sure, but the capital and one-time cost of acquiring and shifting to the modern server would be non-zero, and it would entail some risk. (While OpenVMS is maintained and runs on newer systems, that doesn't mean the software that matters on the existing cluster would run without modification.)
It probably would save operating costs, and probably over a reasonably short window, if it was done successfully, though.
rubitxxx10 · 5h ago
> Could they not get more juice out of a single, modern server?
Maybe the software they use won’t easily run on a modern server.
You could ask them, but you might have to hook up your modem and try to call them. Maybe they have a BBS you could leave your question on.
ccgreg · 3h ago
In 2020 I toured the machine room and those boxes were powered off.
ddahlen · 13h ago
The minor planet center is the clearing house of observations of objects in our solar system. They have announced a new dwarf planet today.
This object appears to be in a very eccentric orbit (0.948), and with an H magnitude of 3.55, so it is likely hundreds of km in diameter.
Ceres for reference has a H magnitude of 3.33 (smaller H is bigger diameter).
Thanks, it helps quite a bit to be able to visualize what they're talking about.
Out at 90 AU, and by the year 3000 is out at 500 AU, and that's still not anywhere near maximum distance. Looked like it was going to be 10,000+ years orbits or longer, and probably out at several 1000 AU at maximum.
Little skeptical it would even orbit normally with how heavily eccentric it is, and the extreme distance at maximum. Way... out beyond the heliopause / heliosheath / termination shock.
Does anyone know if this has its PE in alignment with the other Sedna type objects found?
I think there is a tendency for them to have their PE out to one side and the AP out to the other giving a fairly obvious pattern indicating another larger object is shepherding the others into their orbits.
evil-olive · 12h ago
> This object appears to be in a very eccentric orbit (0.948)
from [0]:
> Before its demotion from planet status in 2006, Pluto was considered to be the planet with the most eccentric orbit (e = 0.248). Other Trans-Neptunian objects have significant eccentricity, notably the dwarf planet Eris (0.44). Even further out, Sedna has an extremely-high eccentricity of 0.855 due to its estimated aphelion of 937 AU and perihelion of about 76 AU
> ...
> Comets have very different values of eccentricities. Periodic comets have eccentricities mostly between 0.2 and 0.7, but some of them have highly eccentric elliptical orbits with eccentricities just below 1; for example, Halley's Comet has a value of 0.967
so possibly an ignorant question, as someone who's interested in astronomy but doesn't follow it very closely - when this is categorized as a dwarf planet, does that include "it might be a comet" as a possibility? or have they already ruled it out as a possible comet through other observations?
Dwarf planet versus comet/asteroid hinges on mass, basically its "enough mass to be roughly round" (technically it's called "hydrostatic equilibrium").
Back from the 1810's to the 1870's or so, most people considered Ceres, Vesta, and things like that to be planets- they were bodies that wandered around the solar system, that meant they were planets. When the numbers started to get into the 20's, everyone decided to create a new category, "asteroid" (Greek for 'star-like') and put all of the smaller things in that. So when Pluto was discovered in 1930 it was slotted right into the planet category. Pluto was discovered mostly by accident, because Clyde Tombaugh was amazing at working the blink comparator, and finding the one dot that moved in between the two pictures of the night sky a few days apart.
However, by the 1990's and 2000's you had computers and digital cameras, which are even better than Clyde at finding things that move, and quickly the number of planets started to go up- and it was clear that once we had thoroughly mapped the ~~Oort Cloud~~ (meant Kuiper Belt, see below) etc. we would have dozens of planets. And so once again astronomers decided to create a new category, just like they had with asteroids a century earlier. This time they drew the line in such a way that Ceres got moved from asteroid to dwarf planet- it has enough mass to be roughly round, so after over a century of being an asteroid it became a dwarf planet.
This is how things always work in science: we discover something, then we discover more of them, and re-categorize everything based on the new discoveries. It's just more noticeable with Pluto because reciting the planets is done by every schoolkid in a way that they don't for subatomic particles or for species of voles or whatever.
hinkley · 11h ago
And that, boys and girls, is how Neil deGrass Tyson got Pluto demoted. (I kid).
elpres · 2m ago
The scientist who demoted Pluto was, in fact, Mike Brown (https://en.wikipedia.org/wiki/Michael_E._Brown), and he wrote a really nice book about it called “How I Killed Pluto and Why It Had It Coming”.
naikrovek · 10h ago
I still think he did it because he wanted to have his name on something significant. He’s a science communicator, not a researcher, and he’s not going to be making any discoveries. So he’s gotta change something that already exists to have his name on something that everyone knows. He had the power to change its status, so he did. I think that’s all it was. I hope I’m wrong but I’ve never heard a really GOOD reason to undo something that was so commonly known and taught. The definition for “planet” could change and Pluto could have been left alone, grandfathered in, in a way. There’s a reason it was discovered first. It’s huge compared to other dwarf planets.
There’s no reason that Pluto couldn’t have remained a proper planet. It’s big enough to be round and its largest moon is big enough to be round. Mars doesn’t have any round moons. Mars is still a planet.
dandelany · 7h ago
He didn't "do it", he was one voice among many astronomers who have been calling for a reclassification for years, the IAU voted and made the decision. It's a little silly calling him out for "doing it" for ego reasons when you are the one implicitly giving him credit for it... He didn't write the definition, he didn't chair the committee, he wasn't even on the committee. All he did was leave it off the list of planets at the Hayden Planetarium, where he was director.
xp84 · 9h ago
> The definition for “planet” could change and Pluto could have been left alone, grandfathered in, in a way
This doesn't sound like a science way of doing things. The definition of planet would have to be literally changed to add "Or has to have been discovered before 19XX" in order to keep Pluto without becoming an unbounded set. If you're annoyed at all the pedants correcting kids or anyone else talking about the nine planets, I'd take it up with them for uselessly debating such a fine distinction, like a chemist arguing about the word "Sodium" on a Nutrition Facts label.
I would argue the colloquial definition has indeed been changed in the above way, in that most people would say that what Mars, Venus, and Pluto have in common is they're all planets, and only a few would remember the odd factoid that the dwarf planet designation was created.
It's okay for the colloquial definition to be different than the scientific one. There isn't any use case where that will harm anyone. It's not like we're chartering flights to "All Planets" where space tourists are going to be ripped off, limited to 8 planets by the technicality and missing out.
naikrovek · 9h ago
You’re probably right, but I still think there’s room for things like this.
What’s a “moon” versus a “planet”? Earth is a moon of Sol, is it not? Why is having a lot of planets a problem in the first place? Why do we have to restrict the definition at all? If 2-3 stars are at the center of a star system, are the planets in that star system planets, or something else? What if they’re small?
This whole scene is ripe for people who want to put their stamp of opinion on something to go nuts arbitrarily.
xp84 · 9h ago
What’s a “moon” versus a “planet”? Earth is a moon of Sol, is it not?
We already have the word "satellite" for "things that go around other things" right? I think "moon" is just "satellite of a planet" for convenience in discussing that subset.
> Why is having a lot of planets a problem in the first place?
I think keeping the number manageable is explicitly something we keep around to help kids grasp the main entities in the solar system. If we just said "there are 235 planets" it would be silly to try to teach them all, so we'd probably just settle for "The top 10 biggest planets" or something. Having a definition instead of a number to bound the set isn't much less arbitrary than teaching the "top 10," but since the long tail clearly starts after #8, "Top 8" would be the only guaranteed stable set to give special treatment to, which is what we've arrived at with the official definition.
MyPasswordSucks · 7h ago
> Earth is a moon of Sol, is it not?
No. The sun is a star, so it doesn't get to have moons. It has planets. If Jupiter started generating heat from nuclear fusion reactions, we'd call Io a planet right before we boiled to death, and with our dying breath we'd add "and also, it's no longer a moon".
Putting a leash on a cat doesn't make it a dog, and both of those creatures have four legs even if you call the tails of each a leg. A planet revolves around a star, a moon revolves around a planet (revolving around a star). There's further elements which make Ceres and Ed White's lost glove not a planet or a moon, respectively, but planets and moons are distinct and non-overlapping categories.
ALittleLight · 2h ago
Why would we be boiling to death in this situation? Jupiter is much further from Earth than the sun is and Jupiter is also much smaller. Heat would increase, but probably not that much.
rantallion · 9h ago
> What’s a “moon” versus a “planet”? Earth is a moon of Sol, is it not?
Planets orbit stars. Moons orbit planets. That's a clear and easy distinction. Planet vs dwarf planet isn't so clear to most.
amanaplanacanal · 7h ago
Don't planets and moons both orbit their center of mass? The distinction only seems to make sense if the masses of the two bodies are far apart. If they have similar mass, which is the moon and which the planet?
No comments yet
naikrovek · 7h ago
What’s a moon that orbits a moon? Doesn’t that make the orbited moon a planet? Pluto has moons. But it’s not a planet? ???
If a super massive planet and two stars orbit each other in the center of a star system, all the planets that orbit those stars are moons then technically, right?
This is all super fuzzy and completely arbitrary. These concepts are constructs. Humans could make them better. Instead, everyone decided to make it all worse.
x______________ · 4h ago
Don't forgot about moonlets!
gamblor956 · 4h ago
No. A star is not a planet. The bodies orbiting the stars are planets, or dwarf planets, asteroids or comets. Bodies orbiting them are moons. Bodies orbiting the moons don't have a name.
calmbell · 9h ago
Eris is essentially the same size as Pluto and has a larger mass.
naikrovek · 9h ago
Then ADD Eros. Don’t remove Pluto.
p_j_w · 8h ago
Why?
simondotau · 39m ago
Stop agonising over metadata. Pluto is still there and it’s not going anywhere.
XorNot · 10h ago
Isn't that kind of the issue though? Pluto's moon isn't just round it's about half the size of Pluto itself such that the Pluto-Charon system orbits around a point in space between the two bodies.
naikrovek · 9h ago
Jupiter and the sun orbit a barycenter, too. Jupiter is a planet.
XorNot · 7h ago
And the sun is a star. The point is the category exists to be useful: if Pluto is a planet then a ton of other stuff is technically a planet.
metalman · 9h ago
I prefer to think that Pluto got denounced, and may yet be rehabilitated.MPAPA
AStonesThrow · 11h ago
> thoroughly mapped the Oort Cloud
So it’s interesting that the Oort Cloud is often mentioned as a real thing. Surely there are plenty of bodies discovered which are orthogonal to its existence, but Oort’s “Cloud” itself still enjoys only the status of hypothesis and not reality.
Sadly, even Wikipedia editors seem unable to distinguish between the formal definitions of “hypothesis” vs. “theory” when delivering such a scientific article.
codethief · 11h ago
Oh wow, looks like I'm one of today's lucky 10,000! Thanks so much!
mandevil · 11h ago
You are correct, I meant to say Kuiper Belt, not Oort Cloud, pulled the wrong thing out of my memory. Unlike the Oort Cloud, we are doing a good job of mapping KBO's as we speak.
throwaway2k255 · 9h ago
If the furthest objects of the Oort Cloud are over 3 light years away, it is relatively close to Alpha Centauri.
Is there a chance that Alpha Centauri also has its own cloud that overlaps with it?
Would AC influence the cloud and adjust the orbit of smaller comets?
TheOtherHobbes · 7h ago
There's a chance, but no one knows for sure.
Oort Clouds are mostly empty space, so there wouldn't be much direct interaction. But there would certainly be gravitational effects.
My guess (FWIW) is there's more out there than we suspect, likely including plenty of rogue/wandering planets between systems.
epicureanideal · 11h ago
Very informative, thank you!
hinkley · 11h ago
That wiki page needs some work. The section you linked to describes the eccentricity as a ratio, however the top of the page describes 0 as perfectly circular and 1 as an escape trajectory.
If it were a ratio then 0 would be escape and 1 would be circular.
zamadatix · 7h ago
The "Examples" section doesn't seem to talk about ratios, do you mean the end of the prior "Calculation" section? If so part is just saying you can calculate the ratio of r_a to r_p given you know e and run it through the equation, not that e itself = r_a / r_p (the formula to calculate e from r_a and r_p is higher up in the section).
If not that section, apologies for missing what you're trying to point out - I'm just trying to see what needs to be cleaned up so I can make an edit if needed.
gus_massa · 13h ago
> hundreds of km
How big is that compared with other dwarf planets/ Moons? If you sort all dwarf planets by size, which position does this take (approximately)?
Pluto -> 2300 Km
Ceres -> 950 Km
Fobos(Mars) -> 25 Km
ddahlen · 13h ago
Depends on the albedo, if the H magnitude is a good measurement, then it is probably between 300-700km. These are rough bounds, its highly dependent on how reflective it's surface is (albedo).
With an orbit somewhere around 28k years, it reached perihelion in about 1931, at 45 au from the Sun.
kbelder · 12h ago
So it's roughly in the closest 200-year period out of 28,000 years. That means it spends 99.3% of it's orbit further away than now, and thus harder to find.
Simplistic odds would seem to imply that there's over a hundred more dwarf planets just like this but further away, so we just haven't seen them.
hnuser123456 · 12h ago
I really hope we can get some more sensitive and wider telescopes to look deeper into the Oort cloud. At those distances, sunlight is comparable to a full moon or less, surface temperatures are only tens of kelvin. And yet they're still less than 1% of the distance to the next star.
gus_massa · 12h ago
[I'm lost with all the recent discoveries.]
Assuming 500Km, is in in the top 10 by size/mass[1][2]? Top 100? Top 1000? Top 1000000?
[1] Yes I know it's not the same. Whatever criteria is easier to measure.
Does the 0.984 eccentricity orbit imply anything? That's close to eccentricity of 1, which is a parabolic path, not gravitationally bound to the sun.
hnuser123456 · 12h ago
Going off the SMA and eccentricity, part of its orbit is "relatively" close to the sun, ~ 45 AU, about 1.5x the distance to Neptune (~ 30 AU), and the other half of its orbit is very, very far away, ~ 1700 AU, over 50 times the distance to Neptune, but still less than 1% of the distance to the next star.
When it's in the faraway part of its orbit, it is moving very slowly, probably only tens of meters per second, but it's still close enough to the sun to eventually fall back in for another loop.
However, if something else dense enough got close enough out there, it would be easily perturbed and have its whole orbit altered, or even be ejected.
But interstellar space is pretty void of wandering solid bodies, so it keeps falling back towards the sun.
SJC_Hacker · 8h ago
> But interstellar space is pretty void of wandering solid bodies, so it keeps falling back towards the sun.
As far as we know ... we don't know how many rogue planets are out there ... mayb be as numerous as the number of stars or even greater
ChuckMcM · 12h ago
"That's no moon" :-). But more seriously, just another giant lump of stuff swinging around the solar system. I am not an astronomer, so I'm not sure about some of the things I'm reading in that report but to me, it seems to be in the solar ecliptic. But its far enough away even at perigee that the only thing of note it might interact with would be Pluto.
I suppose that flying through the Oort cloud it might periodically launch ice balls into the inner solar system.
dabluecaboose · 9h ago
> But its far enough away even at perigee
Minor astrodynamics nit: "perigee" is a term specific to Earth. The generic term for all bodies is "periapsis", and the term for the Sun is "perihelion"
(Astrodynamics terms generally take from the Greek, rather than Latin)
rich_sasha · 11h ago
It boggles my mind when I look up at the Moon, that in fact it's a massive rock travelling at something like 2,000 mph, always trying to fall onto the Earth, and missing it all the time.
mgiampapa · 11h ago
If my goal was to fall into the earth and kept missing I would be depressed too. Each try it misses by slightly more and it's orbital distance increases. How sad is that?
Also, I like to anthropomorphize inanimate objects because secretly they hate it.
No comments yet
BurningFrog · 7h ago
Earth is also constantly failing at falling into the Moon.
Why did we have to evolve in such a loser system??
yieldcrv · 11h ago
its getting further away, if it helps your understanding of the situation better
“falling into” was never part of the equation
brudgers · 12h ago
only thing of note it might interact with would be Pluto
Is Pluto a planet again, or not? Honest question because
I don't keep up on these things because they have no practical effect other than drama...and I try to avoid drama.
kulahan · 11h ago
No. It’s smaller than other moons in our solar system. It’s never going to be a planet again, but a planetoid, dwarf planet, or even asteroid is appropriate.
GMoromisato · 7h ago
Just to be pedantic, Mercury is also "smaller than other moons in our solar system"
And never is a long time, especially for something as fickle as human classification.
kulahan · 5h ago
You’re right, it’s about gravitational domination.
d_silin · 11h ago
For the curious.
Periapsis, au: 45.241
Apoapsis, au: 1714.759
Period, years: 26106.07
silverfrost · 10h ago
26000 year period and yet it has still been around the sun 2000+ times since the dinosaurs went extinct. Make me feel a bit insignificant and awed at the same time.
d_silin · 10h ago
It comes to Earth closer than Pluto, btw.
zamadatix · 8h ago
Specifically: when this object is at its closest and Pluto is at its farthest then this object can be the one closer to Earth. Pluto comes the closest of the two overall though.
ddahlen · 11h ago
I got a bit too excited with this one, this is may not be a full on dwarf planet, but it is a very large object. There are only a small number (about 10-20) objects in our solar system of this size. Its the first big one we have found in a number of years.
calmbell · 7h ago
By "small number (about 10-20) objects in our solar system of this size" you are referring to the class of objects of a similar size rather than the largest objects in the solar system?
Sorry for a stupid question: could it be "the planet X", or is it too light / in a wrong orbit?
mandevil · 11h ago
This is a good question to ask. It can't be, for the reasons you guessed.
This is not the first time this sort of thing has happened. When Pluto was found by Clyde Tombaugh he was looking for Planet Nine, which Percival Lowell had calculated must be present based on the orbits of the outer planets. But it was quickly realized that Pluto was too small and in the wrong orbit for it be Lowell's deduced planet. (And even then they worked with a too high estimate of Pluto's mass, it wasn't until the 1978 discovery of Charon that we got a good estimate of Pluto's mass. It is hard to get a good mass estimate without something else in orbit around it.)
The Pioneer and Voyager missions gave us much better estimates of the masses of the gas giants, and my understanding is that if you go back and redo Lowell's calculations with those correct masses, his planet disappears. That's my best guess as to Planet X, that our constants are wrong in some way, but we'll see.
hinkley · 11h ago
One of the other theories for Planet X I believe has been debunked as absense of evidence. There are gaps in the documented bodies orbiting the sun that could imply an object clearing orbits, but they were dismissed instead as sampling errors - there are parts of the sky that are easier to catalog than others, and so of course we have cataloged the easy parts more thoroughly. We need observation stations in a sun orbit to see the parts we can’t see easily from an earth orbit.
atlgator · 3h ago
It is a very odd orbit. Obviously it doesn't match the expected mass, but the orbit makes you wonder what else might be out there. As someone else posted:
> The Minor Planet Electronic Circulars contain information on unusual minor planets, routine data on comets and natural satellites, and occasional editorial announcements. They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. > > Prepared using the Tamkin Foundation Computer Network
Looking up the Tamkin Foundation Computer Network: https://www.minorplanetcenter.net/iau/Ack/TamkinFoundation.h...
> The OpenVMS cluster consists of nine single-CPU workstations and one four-CPU server. All the machines are running the extremely robust and secure OpenVMS operating system. The twelve Alpha-based machines are arranged as an OpenVMS Cluster, allowing all machines to share disk storage, execution and batch queues and other resources, as well as simplifying system management.
Assuming "Alpha-based machines" is referring to the DEC Alpha, these computers are ~30 years old. https://en.wikipedia.org/wiki/DEC_Alpha
I can see how they may be still stuck on Alphas because unless they can somehow simply recompile for x86-64 OpenVMS, it’s a complete rewrite from scratch.
They could probably get more performance out of one core on a modern phone, never mind a single modern server. But you see some really old systems in a lot of equipment, not because the porting costs are expensive, but the certification of proving the new system works the same is more than the operational cost of the legacy equipment.
It probably would save operating costs, and probably over a reasonably short window, if it was done successfully, though.
Maybe the software they use won’t easily run on a modern server.
You could ask them, but you might have to hook up your modem and try to call them. Maybe they have a BBS you could leave your question on.
This object appears to be in a very eccentric orbit (0.948), and with an H magnitude of 3.55, so it is likely hundreds of km in diameter. Ceres for reference has a H magnitude of 3.33 (smaller H is bigger diameter).
If you want to know what H means: https://en.wikipedia.org/wiki/Absolute_magnitude#Solar_Syste...
https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2017%...
Out at 90 AU, and by the year 3000 is out at 500 AU, and that's still not anywhere near maximum distance. Looked like it was going to be 10,000+ years orbits or longer, and probably out at several 1000 AU at maximum.
Little skeptical it would even orbit normally with how heavily eccentric it is, and the extreme distance at maximum. Way... out beyond the heliopause / heliosheath / termination shock.
https://arxiv.org/abs/2505.15806
The preprint announcing the discovery lists the semi-major axis as 838 au, so the major axis is 1676 au and aphelion is about 1630 au.
https://arxiv.org/abs/2505.15806
I think there is a tendency for them to have their PE out to one side and the AP out to the other giving a fairly obvious pattern indicating another larger object is shepherding the others into their orbits.
from [0]:
> Before its demotion from planet status in 2006, Pluto was considered to be the planet with the most eccentric orbit (e = 0.248). Other Trans-Neptunian objects have significant eccentricity, notably the dwarf planet Eris (0.44). Even further out, Sedna has an extremely-high eccentricity of 0.855 due to its estimated aphelion of 937 AU and perihelion of about 76 AU
> ...
> Comets have very different values of eccentricities. Periodic comets have eccentricities mostly between 0.2 and 0.7, but some of them have highly eccentric elliptical orbits with eccentricities just below 1; for example, Halley's Comet has a value of 0.967
so possibly an ignorant question, as someone who's interested in astronomy but doesn't follow it very closely - when this is categorized as a dwarf planet, does that include "it might be a comet" as a possibility? or have they already ruled it out as a possible comet through other observations?
0: https://en.wikipedia.org/wiki/Orbital_eccentricity#Examples
Back from the 1810's to the 1870's or so, most people considered Ceres, Vesta, and things like that to be planets- they were bodies that wandered around the solar system, that meant they were planets. When the numbers started to get into the 20's, everyone decided to create a new category, "asteroid" (Greek for 'star-like') and put all of the smaller things in that. So when Pluto was discovered in 1930 it was slotted right into the planet category. Pluto was discovered mostly by accident, because Clyde Tombaugh was amazing at working the blink comparator, and finding the one dot that moved in between the two pictures of the night sky a few days apart.
However, by the 1990's and 2000's you had computers and digital cameras, which are even better than Clyde at finding things that move, and quickly the number of planets started to go up- and it was clear that once we had thoroughly mapped the ~~Oort Cloud~~ (meant Kuiper Belt, see below) etc. we would have dozens of planets. And so once again astronomers decided to create a new category, just like they had with asteroids a century earlier. This time they drew the line in such a way that Ceres got moved from asteroid to dwarf planet- it has enough mass to be roughly round, so after over a century of being an asteroid it became a dwarf planet.
This is how things always work in science: we discover something, then we discover more of them, and re-categorize everything based on the new discoveries. It's just more noticeable with Pluto because reciting the planets is done by every schoolkid in a way that they don't for subatomic particles or for species of voles or whatever.
There’s no reason that Pluto couldn’t have remained a proper planet. It’s big enough to be round and its largest moon is big enough to be round. Mars doesn’t have any round moons. Mars is still a planet.
This doesn't sound like a science way of doing things. The definition of planet would have to be literally changed to add "Or has to have been discovered before 19XX" in order to keep Pluto without becoming an unbounded set. If you're annoyed at all the pedants correcting kids or anyone else talking about the nine planets, I'd take it up with them for uselessly debating such a fine distinction, like a chemist arguing about the word "Sodium" on a Nutrition Facts label.
I would argue the colloquial definition has indeed been changed in the above way, in that most people would say that what Mars, Venus, and Pluto have in common is they're all planets, and only a few would remember the odd factoid that the dwarf planet designation was created.
It's okay for the colloquial definition to be different than the scientific one. There isn't any use case where that will harm anyone. It's not like we're chartering flights to "All Planets" where space tourists are going to be ripped off, limited to 8 planets by the technicality and missing out.
What’s a “moon” versus a “planet”? Earth is a moon of Sol, is it not? Why is having a lot of planets a problem in the first place? Why do we have to restrict the definition at all? If 2-3 stars are at the center of a star system, are the planets in that star system planets, or something else? What if they’re small?
This whole scene is ripe for people who want to put their stamp of opinion on something to go nuts arbitrarily.
We already have the word "satellite" for "things that go around other things" right? I think "moon" is just "satellite of a planet" for convenience in discussing that subset.
> Why is having a lot of planets a problem in the first place?
I think keeping the number manageable is explicitly something we keep around to help kids grasp the main entities in the solar system. If we just said "there are 235 planets" it would be silly to try to teach them all, so we'd probably just settle for "The top 10 biggest planets" or something. Having a definition instead of a number to bound the set isn't much less arbitrary than teaching the "top 10," but since the long tail clearly starts after #8, "Top 8" would be the only guaranteed stable set to give special treatment to, which is what we've arrived at with the official definition.
No. The sun is a star, so it doesn't get to have moons. It has planets. If Jupiter started generating heat from nuclear fusion reactions, we'd call Io a planet right before we boiled to death, and with our dying breath we'd add "and also, it's no longer a moon".
Putting a leash on a cat doesn't make it a dog, and both of those creatures have four legs even if you call the tails of each a leg. A planet revolves around a star, a moon revolves around a planet (revolving around a star). There's further elements which make Ceres and Ed White's lost glove not a planet or a moon, respectively, but planets and moons are distinct and non-overlapping categories.
Planets orbit stars. Moons orbit planets. That's a clear and easy distinction. Planet vs dwarf planet isn't so clear to most.
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If a super massive planet and two stars orbit each other in the center of a star system, all the planets that orbit those stars are moons then technically, right?
This is all super fuzzy and completely arbitrary. These concepts are constructs. Humans could make them better. Instead, everyone decided to make it all worse.
So it’s interesting that the Oort Cloud is often mentioned as a real thing. Surely there are plenty of bodies discovered which are orthogonal to its existence, but Oort’s “Cloud” itself still enjoys only the status of hypothesis and not reality.
https://en.wikipedia.org/wiki/Oort_cloud
Sadly, even Wikipedia editors seem unable to distinguish between the formal definitions of “hypothesis” vs. “theory” when delivering such a scientific article.
Is there a chance that Alpha Centauri also has its own cloud that overlaps with it?
Would AC influence the cloud and adjust the orbit of smaller comets?
Oort Clouds are mostly empty space, so there wouldn't be much direct interaction. But there would certainly be gravitational effects.
My guess (FWIW) is there's more out there than we suspect, likely including plenty of rogue/wandering planets between systems.
If it were a ratio then 0 would be escape and 1 would be circular.
If not that section, apologies for missing what you're trying to point out - I'm just trying to see what needs to be cleaned up so I can make an edit if needed.
How big is that compared with other dwarf planets/ Moons? If you sort all dwarf planets by size, which position does this take (approximately)?
Pluto -> 2300 Km
Ceres -> 950 Km
Fobos(Mars) -> 25 Km
With an orbit somewhere around 28k years, it reached perihelion in about 1931, at 45 au from the Sun.
Simplistic odds would seem to imply that there's over a hundred more dwarf planets just like this but further away, so we just haven't seen them.
Assuming 500Km, is in in the top 10 by size/mass[1][2]? Top 100? Top 1000? Top 1000000?
[1] Yes I know it's not the same. Whatever criteria is easier to measure.
[2] I guess not top 10, but I have no idea about the current knowledge of the long tail. Fake Edit: I took a look at https://en.wikipedia.org/wiki/List_of_possible_dwarf_planets So between 20 and 30???
When it's in the faraway part of its orbit, it is moving very slowly, probably only tens of meters per second, but it's still close enough to the sun to eventually fall back in for another loop.
However, if something else dense enough got close enough out there, it would be easily perturbed and have its whole orbit altered, or even be ejected.
But interstellar space is pretty void of wandering solid bodies, so it keeps falling back towards the sun.
As far as we know ... we don't know how many rogue planets are out there ... mayb be as numerous as the number of stars or even greater
I suppose that flying through the Oort cloud it might periodically launch ice balls into the inner solar system.
Minor astrodynamics nit: "perigee" is a term specific to Earth. The generic term for all bodies is "periapsis", and the term for the Sun is "perihelion"
(Astrodynamics terms generally take from the Greek, rather than Latin)
Also, I like to anthropomorphize inanimate objects because secretly they hate it.
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Why did we have to evolve in such a loser system??
“falling into” was never part of the equation
Is Pluto a planet again, or not? Honest question because I don't keep up on these things because they have no practical effect other than drama...and I try to avoid drama.
And never is a long time, especially for something as fickle as human classification.
Periapsis, au: 45.241
Apoapsis, au: 1714.759
Period, years: 26106.07
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This is not the first time this sort of thing has happened. When Pluto was found by Clyde Tombaugh he was looking for Planet Nine, which Percival Lowell had calculated must be present based on the orbits of the outer planets. But it was quickly realized that Pluto was too small and in the wrong orbit for it be Lowell's deduced planet. (And even then they worked with a too high estimate of Pluto's mass, it wasn't until the 1978 discovery of Charon that we got a good estimate of Pluto's mass. It is hard to get a good mass estimate without something else in orbit around it.)
The Pioneer and Voyager missions gave us much better estimates of the masses of the gas giants, and my understanding is that if you go back and redo Lowell's calculations with those correct masses, his planet disappears. That's my best guess as to Planet X, that our constants are wrong in some way, but we'll see.
https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2017%...